In a setback for foes of a controversial Bush administration wiretapping program, a federal appeals court on Friday threw out an American Civil Liberties Union lawsuit that alleged illicit snooping on Americans' calls and e-mails.

The move marked the first time an appeals court has weighed in on the numerous pending challenges to the spy program. Friday's decision isn't expected to have any direct impact on two related cases pending in the 9th Circuit Court of Appeals and more than 40 others that have been consolidated for consideration in a San Francisco district court.

"It is important to emphasize that the court today did not uphold the legality of the government's warrantless surveillance activity."

--Steven Shapiro, ACLU legal director

The U.S. Department of Justice was quick to praise Friday's decision, which it said "confirms that plaintiffs in this case cannot seek to expose sensitive details about the classified and important Terrorist Surveillance Program."

The agency already succeeded last July in shutting down another ACLU suit, which accused AT&T of illegally divulging the telephone records of its customers to government spies, by asserting that allowing the case to move forward would imperil national security. (By contrast, a federal judge in California hasn't allowed that argument to halt another suit against AT&T involving the Electronic Frontier Foundation.)

ACLU Legal Director Steven Shapiro said his organization had not ruled out petitioning the U.S. Supreme Court for another look at the 6th Circuit's action.

"As a result of today's decision, the Bush administration has been left free to violate the Foreign Intelligence Surveillance Act, which Congress adopted almost 30 years ago to prevent the executive branch from engaging in precisely this kind of unchecked surveillance," Shapiro said in a statement. "It is important to emphasize that the court today did not uphold the legality of the government's warrantless surveillance activity."

The ACLU and the journalists, scholars, criminal defense attorneys and Islamic-Americans it represented had argued that the NSA program, which came to light in a November 2005 New York Times report, was trampling on federal laws and the plaintiffs' constitutional rights to free speech and privacy.

Their arguments rested on what they called a "well-founded belief" that the government was tapping their regular overseas communications--some of which, because of the nature of the plaintiffs' professions, they have an ethical duty to keep confidential--without the necessary court approval.

Judges Alice Batchelder and Julia Smith Gibbons, both appointed by President Ronald Reagan, concluded in separate opinions that the parties that sued the NSA didn't have standing to bring their case in the first place. They ordered that the suit be sent back to a lower court and roundly dismissed.

The two judges' reasoning, which differs at times, boils down to one general result: the parties that sued the NSA hadn't shown adequate evidence that they have been "personally" subject to the eavesdropping program. Even if the plaintiffs had wanted to supply evidence to back such a claim, they would have been stymied by the government's assertion of its "state secrets" privilege, which permits the derailing of lawsuits that might otherwise lead to the disclosure of military secrets.

"Evidence arguably protected by the state secrets privilege may well be relevant to the reasonableness of the plaintiffs' fear," Gibbons wrote. "Whether that evidence is favorable to plaintiffs or defendants, its unavailability requires dismissal (of the case)."